The work was previously credited only to Ghirlandaio's workshop, although it was known that Michelangelo had painted the saint.

But the New York art deal who bought it for $2 million at Sotheby's in 2008 was convinced it was a Michelangelo piece and had experts at the Metropolitan Museum of Art examine and clean it, according to the New York Times.

"When it was cleaned, it was X-rayed, infrared photography was done, and that's when we realized that it is indeed a Michelangelo, and the evidence for this is absolutely overwhelming,"said Eric Lee, director of the Kimbell.

The painting is not an exact copy of Schongauer's engraving. It is larger, and Michelangelo made changes that are evident in the underdrawings. He changed the club to a firebrand and used a different angle.

"The Torment of Saint Anthony" also has a landscape at the bottom, more dramatic monsters and St. Anthony has a different expression on his face than in the original, according to the New York Times.

The Kimbell Art Museum purchased the painting in the spring for an undisclosed amount. It was briefly shown at the Metropolitan Museum of Art in New York this summer before returning home to North Texas.

"When I started my job at the Kimbell six months ago, never did I think this would be possible, acquiring a painting by Michelangelo, but here it is," Lee said.

The painting will be on display beginning Saturday during the Day in the District, when admission is free to seven museums in Fort Worth.